In the years following the American Revolutionary War, the noncommissioned officer corps continued to evolve and adapt with time.

In February 1812, Congress ordered the creation of a 50,000-man volunteer army. When war was declared on Great Britain in June 1812, there were roughly 7,000 men in the regular service; many were under the command of senior officers who lacked experience in combat or leading troops.

It fell on the NCO corps, specifically corporals, who were the primary trainers at the time, to prepare the Soldiers for combat against the British.

For two years, war raged across America with the Battle of New Orleans being the last military conflict in January 1815.

The Treaty of Ghent was signed in Paris in December 1814 ending the War of 1812; yet, with communications taking a great amount of time to reach their destination, both armies were unaware the war had ended.

After the war, Congress and the War Department continued to institute new programs and publications to enhance the NCO corps.

The War Department first acknowledged the NCO chevrons in 1821.

Sergeants major and quartermaster sergeants wore a worsted chevron on each arm above the elbow; sergeants and senior musicians, wore one on each arm below the elbow and corporals wore one on the right arm above the elbow. The practice lasted until 1829.

In 1824, at Fort Monroe, Va., the first school for centralized Soldier instruction was opened. Instead of training officers and NCOs individually, the school focused on training entire units. Though it was suspended from time to time, this became the precursor for all centralized modern technical training Soldiers now receive.

A year later, in 1825, the first attempt at a systematic method for NCO selection was made. Unless overriding considerations came up, regimental commanders were expected to accept the company commanders' recommendations for company NCOs.
In 1829, The Abstract of Infantry Tactics was published and provided new instructions for training NCOs.

The main goal of the publication was to ensure that all NCOs possessed "an accurate knowledge of the exercise and use of their firelocks, the manual exercise of the Soldier and of firing and marching."

A sixth rank, ordnance sergeant, was added to the NCO ranks in 1832. It was a specialized rank designated to those with the duties of receiving and preserving the ordnance, arms, ammunition and other military stores of the post that he was assigned.

Dragoon regiments, which were considered elite mounted rangers, were created by Congress in 1833.

To show their elite status, Dragoons reintroduced the chevron, with the chevron pointing down on their uniform, for use by NCOs.

In an effort to add more prestige to the NCO corps, a distinctive sword was adopted in 1840. To this day, the model 1840 NCO sword remains in use during special ceremonial occasions.

With the annexation of Texas in 1845, along with America's desire for more land, the Mexican-American war began in 1846.

During the war, the U.S. raised 115,000 troops, of which 73,000 were volunteers. The volunteers often elected their officers and NCOs by popular vote based on public standing or previous military experience.

NCOs often led small detachments against the Mexican Army and Indians to discourage attacks on settlers.

During the war, in 1847, the chevron again was adjusted, this time worn in inverted "V" direction. It would stay this way until the 1850's when the War Department would again make changes to the NCO and their uniforms.

The Mexican-American War officially ended with the Treaty of Guadalupe Hidalgo in February 1848.

After the war, the United States gained over 500,000 square miles to expand, creating a larger area of responsibility for the NCO to defend.

After the Mexican-American War, very few changes occurred for the NCO. It wasn't until 13 years later when the Civil War began that the Army would call upon its "backbone" to lead it in one of the darkest hours in American history.